1. Field of the Invention
The present invention relates to a confocal microscope, which is enabled to measure a stereoscopic shape of a sample by combining an optical microscope and a confocal optical scanner.
2. Description of the Related Art
For example, a Nipkow's disc type confocal microscope apparatus, as shown in FIG. 1A, is well known in the related art. This confocal microscope apparatus is provided with: a microlens array 101, a pinhole array 102 (i.e., Nipkow's disc) and an objective lens 103 for condensing a laser light onto a sample 20; an actuator 104 for moving the objective lens 103 in an optical axis direction (or in a Z-direction, as shown); a camera 106 having a condensing lens 105; and a beam splitter 107 for changing the path of the reflected light coming from the sample through the objective lens 103 and the pinhole array 102, in the direction to the camera 106.
In the configuration, the Z-coordinate of the focused point of the laser light is controlled depending on the position of the objective lens 103 in the Z-direction, and the XY-coordinates of the focused point of the laser light is controlled by turning the microlens array 101 and the pinhole array 102. In other words, the scanning point in the sample 20 to be picked up by the camera 106 can be three-dimensionally controlled depending on the Z-direction position of the objective lens 103 and the turning angles of the microlens array 101 and the pinhole array 102.
In the such a scanning technique of the confocal microscope apparatus, the operations to move the objective lens 103 uniformly in a Z-coordinate increasing direction for a longer period than a plurality of frame periods are started in synchronization with a vertical synchronizing signal of the camera, as produced just after the input of a trigger signal, while turning the microlens array 101 and the pinhole array 102 in synchronization with the vertical synchronizing signal of the camera 106. This scanning technique is described, for example, in JP-A-2002-72102.
In the scanning technique, however, the timing for starting the movement of the objective lens 103 is synchronized with the vertical synchronizing signal, but the movement after the start is performed asynchronously of the vertical synchronizing signal. As a result, it is difficult to control the Z-direction position of the scanning point highly precisely for the individual video frames to be picked up by the camera 106. In the case of the repeated capturing with the movement of the Z-direction position, more specifically, the discrepancy of the Z-direction position is so cumulatively enlarged that the discrepancy can be neither confirmed nor corrected.
In the related art described above, moreover, the individual scanning points are captured by scanning in the XY-directions while changing the Z-coordinate at all times. According to the capturing method by thus changing the Z-coordinate at all times, moreover, the Z-coordinate point can be prevented from being unscanned for all the XY-coordinates so that even a micro structure in the Z-direction can enhance the probability of its appearance at least in the captured images.
In the related art, the coordinates of the objective lens 103 change uniformly, too, even for the time period of the synchronizing signal such as the vertical synchronizing signal, when the capturing is not done in the camera 106. However, that Z-coordinate range in the sample 20, which corresponds to the range for the objective lens 103 to have moved for the synchronizing signal period, is not captured in the least. According to the related art, therefore, a micro structure in the Z-direction may drop out.
Depending on the application of the confocal microscope apparatus, on the other hand, the video frames having picked up the XY-plane of the sample with the Z-coordinate being fixed may be desirably produced individually for the different Z-coordinates. For example, a set of video frames thus produced become as they are the voxels having the XYZ-coordinate system so that they are suited for the processing such as the three-dimensional analysis of the sample 20.
According to the related art thus far described, however, the Z-coordinate always changes, too, for the video pickup period of the camera 106 so that the video frames having picked up the XY-plane of the sample with the Z-coordinate being fixed cannot be produced.